(659e) Sizing of a Packed Reactive Distillation Column for Isoamyl Butyrate Production Using an Equilibrium Model

Sizing
of a Packed Reactive Distillation Column for Isoamyl Butyrate Production Using
an Equilibrium Model

Jairo
Duran, Karen Cañon, Alejandro López, Álvaro
Orjuela

Grupo
de Procesos Químicos y Bioquímicos. Department of Chemical and
Environmental Engineering. Universidad Nacional de Colombia. Bogotá. Colombia

Reactive
distillation has been considered as an alternative for sustainable process in
the production of green chemicals because their capabilities of reaching high
conversion in equilibrium reactions, flexibility and relatively low costs.
Several studies have pointed the importance of taking into account high-quality
thermodynamic and kinetic parameters in order to obtain reliable estimations on
the performance of the integrated reaction-separation operation. Among
different biobased esters, isoamyl butyrate that is used as green solvent and food
additive can be obtained from renewable raw materials. For instance, fermentation
broths from fuel ethanol production contain up to 2.5% (volume basis) of amyl
alcohols which are currently blended with fuel ethanol or used as fuel for
steam boilers. As a potential upgrading alternative, these alcohols can be
esterified with different acids using a reactive distillation scheme to improve
reaction conversions and energy savings with respect to the traditional
esterification processes.

In
this work, kinetic and phase equilibrium parameters from experimental data were
used to simulate and size a reactive distillation column. NRTL and Hayden
O'Connell models from regressed experimental data were used in phase
equilibrium calculations. Kinetics was measured in a batch reactor using
Amberlyst^® 35 as catalyst. A full factorial design was established
to carry out the kinetic tests. Experimental data were fitted adequately with a
pseudo-homogeneous model. In addition, autocatalytic kinetics was measured
using an identical methodology. The module RADFRAC of Aspen Plus^® was
used in modeling of reactive distillation. A basis of 200.000 kg per year of isoamyl butyrate (food grade, >99% weight) was considered in sizing and
sensibility analyses. Amberlyst^® 35 contained in KATAPAK SP-11® was
considered in the simulation. MELLAPAK-250Y^® was used in non
catalytic packing sections, where autocatalytic kinetics was considered. Column
height was calculated assuming an HETP of 0.5 meters, as reported by several authors.   

According
with simulation results a conversion of butyric acid higher than 96% was
possible. Nevertheless, including a pre-reactor in the scheme, a conversion
higher than 99.1% was observed. Best performance of operation was found when
using a mole excess around 1.5 of isoamyl alcohol to butyric acid in the
system.

Keywords: reactive distillation,
esterification, catalytic packing, ion exchange resin, flooding factor.